Not Applicable
Guillotine type construction industry stud cutters are well known commercially. In the cutters now known, a pair of spaced die blades, with openings in them to accommodate different widths of studs have been fixedly mounted within a frame. A guillotine blade moving through the space separating the plates, sheers the stud. In the present application, xe2x80x9cstudxe2x80x9d is used generically to encompass not only studs used in the walls of buildings, but also floor joists, rafters, gutters, and the like trough-like shapes.
One of the problems with the machines known heretofore arises from the fact that although studs are supposed to come in a variety of standard sizes, the fact is that they vary in width from the standard. Thus, a 3xc2xd inch wide stud may in fact be 3xe2x85x9c or 3⅝ inches wide. In order to accommodate these variations, the openings in the die blades have had to be made wider than any but the largest of the off-sizes for each of the standards; then when a relatively narrow stud is inserted, when the guillotine blade, which has a v-shaped center tooth, comes down, it tends to splay the sidewalls of the stud at the end at which it is cut, and if the largest of the off-sized stud of that standard is cut, the blade tends to bend down the inwardly extending flanges of the stud. Neither of these is desirable. In fact, with most commercial machines, the flanges are unsupported during the cutting, so that they tend to be bent down in any event.
One of the objects of this invention is to provide a machine in which the stud is supported against splaying and the flange is supported against being bent down, regardless of the variation, within limits, from the standard width.
Other objects will become apparent to those skilled in the art in light of the following description and accompanying drawings.
In accordance with this invention, generally stated, in a guillotine blade type stud cutter, with side rails between which the blade moves in a direction lengthwise of the rails, spaced, fixed, parallel back-up or stationary die plates are secured transversely between the side rails. Immediately inboard of the stationary die plates, spaced parallel punch or shear plates, spaced closely to receive between them the blade, are mounted for sliding movement toward and away from one another transversely of the side rails, i.e., parallel to the pairs of stationary die plates. In this embodiment, the stationary die plates have openings in them to receive the walls and flanges of studs of all expected variations in width from the standard of various standard widths. The shear plates also have openings in them, and both the stationary die plates and the shear plates have lip openings to receive the flanges of the studs. Because the shear plates are movable transversely of the machine frame, a stud can be put into the opening, the plates moved until they engage the sidewalls of the stud and then backed off a very small amount, so that the next stud of the same lot can be slid into place without readjusting the spacing of the shear plates. If the side walls of the stud extend at an obtuse angle from a bottom wall, the xe2x80x9cverticalxe2x80x9d openings or slots can be angled complementarily. Both are embraced within the term xe2x80x9csubstantially verticalxe2x80x9d as used to describe the side wall slots in the stationary die plates and shear plates. The flanges of the stud are supported on lip opening defining facing surfaces of the shear plates. The stud to be sheared is supported by the shear plates well within the elastic limits of the stud""s side walls and flanges, so that no splaying of the side walls or permanent bending of the flanges is produced during the shearing process. Generally, all of the studs of a given lot have the same width. If they do not, it is an easy matter to readjust the position of the shear plates.
In the preferred embodiment, a support arm is provided, projecting perpendicularly from the machine frame, and centered with respect to the cutting blade. Studs with closed bottoms aligned along an upper surface of the support bar, can be slid into the slots of the stationary die and the shear plates. An indexing pin is movably mounted along the support bar and clamped in position, so that, when the pin, which is normally spring-biased to that position, is projecting above the surface of the bar, a stud can be pushed against it to position the stud for the exact length desired. The pin is actuated in response to the cutting movement of the blade to retract from its indexing position above the surface of the support bar, so that the stud can easily be withdrawn.